Critical Hits are a common thing seen within battles. Critical Hits increase the damage that is given for any attacking attack. However, there are many variables that alter the chances of Critical Hits as well as the increase in the damage it increases it by.

Prior to Pokémon X & Y, Critical Hits increase the damage to be given by a further 100% making it 200% of normal. This calculation is placed after the Type Effectiveness and STAB is calculated, causing even more of an increase in power. There is however a way of increasing it by a further 100% making it 300% of normal. This is done only with Pokémon that have the ability Sniper. This means that a Super Effective Attack will likely completely floor most Pokémon when critically hit.

However, from Pokémon X & Y, the strength of Critical Hits has been drastically reduced. Instead of doubling the damage, the Critical hits will now do 50% more damage from the standard damage. If you have the ability Sniper, this increases to make the move do 225% of its standard damage.

The chances of Critical Hits are done in stages. There are five stages of which the Critical Hit percentage is calculated. All moves are on Stage 1 apart from a handful on Stage 2. However, with various items, abilities and a combination thereof, you can reach Stage 5 and have a 50/50 chance of hitting with a Critical Hit. Below is a list of the stages and their chances of occuring.

Stage

Gen II-V Percentage

Gen VI-VII Percentage

1

6.25%

6.25%

2

12.5%

12.5%

3

25%

50%

4

33.3%

100%

5

33%

100%

Using Pokémon Amie or Pokémon Refresh also brings an increased chance of Critical Hits

Every move that does damage, either physical or special is part of Stage 1 and thus has a 6.25% chance of causing a Critical Hit. However, there are many things that boost the Critical Hit Ratio.

There is also one special ability that doubles the Critical Hit ratio stage (If normally 1 it becomes 2, if normally 2 it becomes 4). This ability is Super Luck and is only known by Murkrow, Honchkrow, Absol, Tranquill and Unfezant and with Togepi, Togetic and Togekiss getting it as their Hidden Ability. This is the only way to get a stage 5 percentage, by having them with Super Luck, using a move such as Slash and holding a Razor Claw or Scope Lens. The ability Merciless, known by Mareanie and Toxapex, will make it so their moves will always land a Critical Hit on a Poisoned opponent.

Finally, there are two moves which have a Critical Hit ratio of 7 allowing for a 100% Critical Hit ratio. These moves, barring any abilities or moves preventing it, will always result in a Critical Hit.